Shelf



FIG. 1 is a left side perspective view of a shelf showing my new design;

FIG. 2 is a right side perspective view thereof;

FIG. 3 is a bottom perspective view thereof;

FIG. 4 is a top view thereof;

FIG. 5 is a bottom view thereof;

FIG. 6 is a right side view thereof;

FIG. 7 is a left side view thereof;

FIG. 8 is a front view thereof; and,

FIG. 9 is a back view thereof.

The broken lines in the drawings depict portions of the shelf that form no part of claimed design. 

CLAIM The ornamental design for a shelf, as shown and described. 